1. 
Pesticides and plant protection products: One of the main causes of bee deaths is the use of pesticides. Pesticides can directly kill bees or disrupt their ability to navigate and return to the hive.
2. 
Genetically Modified Organisms (GMO): GMO plants can have negative effects on bees. Some studies show that bees consuming nectar or pollen from GMO plants may lose their ability to return to the hive. Additionally, GMO plants may be less nutritious for bees.
3. 
Diseases and parasites: Bee colonies are often affected by various diseases and parasites, such as Varroa mites, which spread viral diseases like chronic and acute bee paralysis.
4. 
Environmental changes: Climate change and environmental degradation also contribute to the decline in bee populations. Poor weather conditions and food shortages can weaken bee colonies.
5. 
Neonicotinoids: These pesticides can disrupt bees' ability to navigate and return to the hive, causing them to often get lost and die.